We've been having a hot and dry spell, and the last few days have been cooler though not really more humid.
My guitar doesn't have a tie block, but a tailpiece that's been the source of buzzing before so that was the first thing I checked. Frett buzz isn't the source here either (that often seems to come from around the bridge too!) because the buzz goes away when I keep my palm away from the guitar and if anything the action has become higher because of the climate conditions (that would explain the need to finger more precisely, I think).
I think I found the culprit. I play with this Brazilian forearm pad with the embedded hard shell, and when my hand is in a position to palm mute this is in subtle contact with the cover plate (see my display pic). Turns out one or 2 of the coverplate screws was/were very slightly lose.
As a former Guzzista I should have known to check my bolts and nuts for the effects of good vibrations!
Gretsch G9240 "Alligator" wood-body resonator converted to non-metal strings (China, 2018?)
Bolink baroque violin (Hilversum, 1982)
Formerly: Brian Cohen baroque violin (London, 1985), Nadegini modern violin (Paris, 1924)